Second generation, orally active, antimalarial, artemisinin-derived trioxane dimers with high stability, efficacy, and anticancer activity

In only two steps and in 63% overall yield, naturally occurring 1,2,4-trioxane artemisinin (1) was converted into C-10-carba trioxane conjugated diene dimer 4. This new dimer was then transformed easily in one additional 4 + 2-cycloaddition step into phthalate dimer 5, and further modification led to bis-benzyl alcohol dimer 7 and its phosphorylated analogues 8 and 9. Bis-benzyl alcohol dimer 7 is the most antimalarially active in vitro, 10 times more potent than artemisinin (1). Bis-benzyl alcohol dimer 7 is approximately 1.5 times more orally efficacious in rodents than the antimalarial drug sodium artesunate and is about 37 times more efficacious than sodium artesunate via subcutaneous administration. Both dimers 5 and 7 are thermally stable neat even at 60 °C for 24 h. Phthalate dimer 5 is very highly growth inhibitory but not cytotoxic toward several human cancer cell lines; both dimers 5 and 7 very efficiently and selectively kill human cervical cancer cells in vitro in a dose-dependent manner with no cytotoxic effects on normal cervical cells.